As a representative example of a wireless power transmission system, a magnetic-field-coupling-type power transmission system that transmits power by utilizing a magnetic field from a primary coil of a power transmission device to a secondary coil of a power reception device is known. In this system, when power is transmitted by magnetic field coupling, the magnitude of the magnetic flux passing through the coils greatly affects the electromotive force and therefore high accuracy is necessary in the relative positional relationship between the primary coil and the secondary coil. In addition, coils are utilized and therefore it difficult to reduce the size of the devices.
On the other hand, an electric-field-coupling-type wireless power transmission system is also known, such as that disclosed in Patent Document 1. The power transmission system described in Patent Document 1 is formed of a power transmission device and a power reception device equipped with passive and active electrodes. The active electrode of the power transmission device and the active electrode of the power reception device are brought close to each other with a gap therebetween, whereby a strong electric field is formed between the two electrodes and the electrodes undergo electric field coupling. Thus, it is possible to transmit power with high transmission efficiency between the power transmission device and the power reception device. In the system described in Patent Document 1, the degree of relative positional accuracy required for the coupling electrodes is comparatively low and it is possible to reduce the size and the thickness of the coupling electrodes.
Patent Document 1: Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2009-531009
An example of the above-described power reception device is an electronic appliance such as a cellular phone or a mobile PC. In recent years, progress has been made in the reducing the size and thickness of such electronic appliances and since a large number of necessary elements such as communication antennas have already been incorporated thereinto, it is difficult to additionally secure space in which to arrange coupling electrodes for power transmission.